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Implementing Data Encryption

Implementing Data Encryption in SQL

Data encryption is a crucial aspect of SQL security. It helps to protect sensitive data from unauthorized access and potential security breaches. In this tutorial, we will be going through the process of implementing data encryption in SQL.

What is Data Encryption?​

Data encryption is a security method where information is encoded and can only be accessed or decrypted by a user with the correct encryption key. Encrypted data, also known as ciphertext, appears scrambled or unreadable to a person or entity accessing without permission.

SQL Server Encryption​

SQL Server provides several methods for data encryption, including:

  • Transparent Data Encryption (TDE)
  • Column-level Encryption
  • Encryption Hierarchy

Transparent Data Encryption (TDE)​

TDE performs real-time I/O encryption and decryption of the data and log files to protect data at rest. When a database is encrypted with TDE, the associated backups and transaction log files are also encrypted.

Here is a basic example of how to use TDE:

CREATE DATABASE MyDatabase
GO
USE MyDatabase;
GO
CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'password';
GO
CREATE CERTIFICATE MyServerCert WITH SUBJECT = 'My DEK Certificate';
GO
USE MyDatabase;
GO
CREATE DATABASE ENCRYPTION KEY
WITH ALGORITHM = AES_128
ENCRYPTION BY SERVER CERTIFICATE MyServerCert;
GO
ALTER DATABASE MyDatabase
SET ENCRYPTION ON;
GO

In this code, we first create a database, then create a master key, and a server certificate. Finally, we create a database encryption key and turn on the encryption.

Column-level Encryption​

Column-level encryption allows you to encrypt sensitive data in a column to ensure that even if data is extracted, it remains confidential.

Here is a basic example of how to use column-level encryption:

USE MyDatabase;
GO
CREATE TABLE Employee
(
    EmployeeId int IDENTITY (1,1),
    FirstName nvarchar(50) NOT NULL,
    LastName nvarchar(50),
    EncryptedPhoneNumber varbinary(128)
)
GO
-- Insert values into the table.
INSERT INTO Employee (FirstName,LastName,EncryptedPhoneNumber) VALUES
    ('John','Doe', EncryptByKey(Key_GUID('PhoneNumber_Key'), '123-456-7890')),
    ('Jane','Doe', EncryptByKey(Key_GUID('PhoneNumber_Key'), '098-765-4321'));
GO

In this code, we create a new table with an encrypted column for the phone number. When inserting data into this table, we use the EncryptByKey function to encrypt the phone number.

Encryption Hierarchy​

SQL Server uses a hierarchy of encryption keys to secure data. At the top is the Service Master Key (SMK), which is generated by SQL Server during the installation. The SMK is used to encrypt the Database Master Key (DMK), which in turn is used to encrypt other keys in the database.

Here is a basic example of how to create a DMK:

USE MyDatabase;
GO
CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'password';
GO

In this code, we simply use the CREATE MASTER KEY command to create a new DMK, secured by a password.

Conclusion​

Data encryption is a key aspect of SQL security. SQL Server provides multiple ways to implement encryption, including TDE and column-level encryption. Using these methods, you can effectively secure your data against unauthorized access and potential security breaches.